This disclosure relates to an improved drive system wherein a first component applies a driving torque to a second component, such as for example a threaded fastener and driver combination, including miniature versions thereof.
The miniature fasteners used in several different types of products, such as Hard Disk Drive (HDD), note books, digital cameras and mobile phones, are significant and they are an important factor in overall productivity, quality and profitability. The drive system on these critical fasteners affects assembly speed, downtime, and the amount of scrapped components.
Prior art includes the following:
EP 1 536 150 discloses a screw tightening construction, as well as a screw and screw lightening tool. Specifically, in a threaded fastener wrenching structure, an inclination angle (α) of an arcuate portion of a fitting protrusion is larger than an inclination angle (β) of an arcuate portion of a recess and a wrenching torque is transmitted through an intermediate portion of the fitting protrusion in an axial direction engaged with an opening edge of the recess. As a result, a diameter dimension of an engaged part is larger than that in the intermediate of the recess engaged with a tip portion of the fitting protrusion in a case of α<β and a smaller force is applied by a constant wrenching torque to the engaged part in inverse proportion to the larger diameter dimension. According to the patent, this restrains a partial damage or a deformation of the fitting protrusion and the recess at the engaged part or allows a small diameter threaded fastener to be efficiently wrenched by higher wrenching torque. A smaller applied force to the engaged part causes a stably wrenched state of the small diameter threaded fastener as a result of a small component force in the axial direction to force apart along an inclination of the arcuate portion, namely, restraining a bit from coming out of the recess.
U.S. Pat. No. 5,598,753 discloses an eagle wing tips tamper-proof fastener and drive tool with complementary driver head contact. A conventional threaded shank is perpendicularly connected to a substantially flat head. The head comprises a plurality of recessed channels numbering three and the channels radially curve outwards from a common center point. In one embodiment, the substantially vertical right and left walls of each channel allow application of torque with the drive tool in both directions. In an alternate embodiment, the substantially vertical right wall and the surface of the substantially inclined left wall allow application of torque with the drive tool to the right only.
U.S. Pat. Nos. 5,957,645, 6,234,914 and 6,367,358 disclose a spiral drive system for threaded fasteners that include driver-engageable surfaces on the head end of the fastener in which at least some of the driver-engageable surfaces are defined by a spiral segment. According to the patents, the driver-engageable surfaces arc configured to maximize torque transmission while spreading the driving load over a broad driver-fastener interface to reduce the risk of development of high stress regions. The patents also disclose drivers and related tooling.
U.S. Pat. Nos. 3,122,963 and 3,658,105 also disclose screws having a recess formed in the head.